import java.util.*;

public class Solution5 {
    public List<String> topKFrequent(String[] words, int k) {
        HashMap<String, Integer> map = new HashMap<>();
        for (String word : words) {
            map.put(word, map.getOrDefault(word, 0) + 1);
        }

        //2. 建立小根堆
        PriorityQueue<Map.Entry<String,Integer>> minHeap = new PriorityQueue<>(new Comparator<Map.Entry<String, Integer>>() {
            @Override
            public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {
                if(o1.getValue().compareTo(o2.getValue()) == 0) {
                    return o2.getKey().compareTo(o1.getKey());
                }
                return o1.getValue().compareTo(o2.getValue());
            }
        });
        //3.遍历map
        for(Map.Entry<String,Integer> entry : map.entrySet()) {
            if(minHeap.size() < k) {
                minHeap.offer(entry);
            }else {
                Map.Entry<String,Integer> top = minHeap.peek();
                if(top.getValue().compareTo(entry.getValue()) < 0) {
                    minHeap.poll();
                    minHeap.offer(entry);
                }else if(top.getValue().compareTo(entry.getValue()) == 0) {
                    if(top.getKey().compareTo(entry.getKey()) > 0) {
                        minHeap.poll();
                        minHeap.offer(entry);
                    }
                }
            }
        }
        ArrayList<String> list = new ArrayList<>();

        for (int i = 0; i < k; i++) {
            Map.Entry<String,Integer> tmp = minHeap.poll();
            list.add(tmp.getKey());
        }
        Collections.reverse(list);
        return list;
    }
}
